Some proteins are composed of two or more polypeptides. Suppose the DNA template strand sequence 3′-TACGTAGGCTAACGGAGTAAGCTAACT-5′ produces a polypeptide that joins in pairs to form a functional protein.
What term is used to identify a functional protein like this one formed when two identical polypeptides join together?

Verified step by step guidance

1. Step 1: Understand the problem. The question is asking for the term used to describe a functional protein formed when two identical polypeptides join together. This involves understanding protein structure and assembly.
2. Step 2: Recall the concept of protein quaternary structure. Proteins can have up to four levels of structure: primary, secondary, tertiary, and quaternary. The quaternary structure refers to the arrangement of multiple polypeptide chains (subunits) in a protein.
3. Step 3: Identify the specific case described in the problem. The protein in question is formed by the joining of two identical polypeptides. This type of protein is referred to as a 'homodimer.'
4. Step 4: Define the term 'homodimer.' A homodimer is a protein complex formed when two identical polypeptide chains (subunits) bind together to create a functional protein.
5. Step 5: Relate the term to the problem. Since the functional protein described in the problem is formed by two identical polypeptides joining together, the correct term to describe it is 'homodimer.'

Key Concepts

Polypeptide

A polypeptide is a chain of amino acids linked by peptide bonds, which are formed during the process of translation in protein synthesis. Polypeptides fold into specific three-dimensional structures to become functional proteins. The sequence of amino acids in a polypeptide is determined by the corresponding mRNA, which is transcribed from DNA.

Dimer

A dimer is a type of protein complex formed when two identical or similar polypeptides (monomers) join together. This interaction can occur through various types of bonding, such as hydrogen bonds or disulfide bridges, and is crucial for the protein's functionality. Dimers can exhibit unique properties that differ from those of individual polypeptides.

Protein Structure

Protein structure refers to the specific arrangement of amino acids in a polypeptide chain, which determines its function. Proteins have four levels of structure: primary (amino acid sequence), secondary (local folding patterns), tertiary (overall 3D shape), and quaternary (assembly of multiple polypeptides). Understanding these structures is essential for grasping how proteins interact and function in biological systems.